57. Brown, Jr. R. M. 1975. Cyanophycean
virus LPP-1. Cytopathic effects in Plectonema boryanum.
Encyclopaedia Cinematographica. Film E 1746 des Inst. Wiss. Film,
Göttingen. Research Film 8:494-502.
57. General Remarks
Algal viruses, while widespread in sewage oxidation ponds and large bodies of freshwater, had not been described until 1964, when SAFFERMAN and MORRIS [4] were able to isolate an infectious agent and to characterize it on the basis of its composition and structure. The host specificity of the virus was confined to three closely related genera of the Oscillatoriales, namely, Lyngbya, Plectonema, and Phormidium. Therefore, the virus was given the name LPP-1 to denote the genera of the host range. Since this initial report, more than 40 papers dealing with various aspects of algal viruses have been published. For the most complete review on this subject to date, see the publication by BROWN [2]. Only the DNA viruses which infect cyanophycean algal cells have been thoroughly characterized. Viruses attacking eukaryotic algal cells have been reported, but to date no one has been successful in isolating and transmitting the infection with the purified and isolated virus. Thus, we know more about cyanophycean algal viruses since they infect prokaryotic hosts much in the same manner as the bacteriophages. The LPP-l virus is a small icosohedron (580 A in diameter) with a short, non-descriptive tail. The infection begins with adsorption to the host cell wall. The tail injects the DNA into the host cell, and replication (which is dependent upon the energy-requiring products of photosynthesis) is completed within 24 hrs., much longer in comparison with the bacteriophage replication. Little is known about the cytology of the infection process (BROWN [1], SMITH[6]) but it is believed that the viral DNA, once injected into the host, migrates to the nucleoplasm where viral DNA copies are made. Then the new viral DNA migrates through the photosynthetic lamellae to the periphery, where development of the virogenic stroma occurs. This migration in Plectonema is fortuitous, because during the course of it, photosynthetic lamellae are displaced and produce an unfailing morphological sign of infection. The LPP-1 virus system has a distinct advantage over the bacteriophage system when attempting to trace the morphology of the infection process because the host cells are larger than bacteria, and they have distinctive morphology the internal changes of which can be monitored at the light microscopic level during the course of infection. This film is the first account of the morphology of the infection process by an algal virus. Because of the increasing -awareness of this interesting virus and its probable importance in the freshwater ecosystem, the writer sought to document stages of the infection process with time-lapse cinematography, using the best available optical methods for critical resolution.